Load Balancing the Dashboard server
Architecture
The Panintelligence Dashboard is made up of 6 different services or components:
MariaDB database to store the PiDashboard configuration
Core Dashboard (served by tomcat)
Excel Reader to use Excel as a data source
Renderer to convert charts into PDF/Word/PPT/PNG.
Pirana that serves as the machine-learning Analytics engine
Scheduler to support PiReports with sending reports at given recurrences
Assuming you want the architecture below:
Where each component may or may not share a machine.
Pirana (as pictured above), Scheduler, Renderer and Excel Reader components are stateless so they do not require session synchronisation if you want to load-balance them.
We highly recommend that you load balance Pirana as well, even if you keep it in one machine as it helps it take advantage of multiple cores.
Configuring the Dashboard
You’ll have to tell the dashboard where its database lives, what the session cookie name is and, if you want to use session sync, the tomcat cluster. Currently you’ll always need to edit at least 1 XML configuration file.
Using containers
For containers you can configure them using environment variables but you’ll still need to edit one XML file for now.
Configuring the database location
You can use environment variables to configure where the database lives:
| Database host |
| Database port |
| Database username |
| Database password |
These can be specified as per the instructions on our Docker Deployments repository.
Configuring the session cookie name
If any of the dashboards is set to a different port than the others, you might have to check that all nodes are setting the same cookie. To do this, make sure the following file is configured as a volume for ease of editing:
<dashboard installation>/Dashboard/tomcat/conf/context.xml
Then edit the following line
<Context sessionCookieName="DASHBOARDSESSIONID8224">
The sessionCookieName
can be anything you like as long as it’s the same for all nodes.
Using native hosts
Configuring the database location
You can use the same environment variables as defined in “Using Containers” or you can edit the configuration files yourself like below.
You need to specify the database URL on the tomcat configuration files, i.e. you’ll need to edit the following XML files:
<dashboard installation>/Dashboard/tomcat/conf/Catalina/localhost/panMISDashboardWebServices.xml
<dashboard installation>/Dashboard/tomcat/conf/Catalina/localhost/panSecurity.xml
<dashboard installation>/Dashboard/tomcat/conf/Catalina/localhost/pi.xml
With an editor, change all entries in those files with the string
to
where database
is the IP or domain to your database machine and port
is the port where the database is listening to.
Configuring the session cookie name
If any of the dashboards is set to a different port than the others, you might have to check that all nodes are setting the same cookie. To do this, check the following file:
Verify that the following line is the same across all your nodes:
The sessionCookieName
can be anything you like as long as it’s the same for all nodes.
Configuring the Dashboard Load Balancer
With nginx
Edit your nginx.conf
or your individual site configuration and add an ‘upstream’ section:
And change your server section to proxy requests to the upstream block you’ve configured:
For the complete nginx config, see attached nginx.conf (link at the bottom).
Access your load balancer and you should see the dashboard.
Configuring session sharing
With nginx
Modify your upstream with the ip_hash
directive:
Don’t use ip_hash
if it’s possible that two clients could share an IP (such as if they’re on a NAT)
This should work on most cases, but if it doesn't suit your scenario see nginx's documentation about session persistence, or see the tomcat config below.
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